protected DbExistsExpression UpdateExists(DbExistsExpression exists,
DbSelectExpression select)
{
if (select != exists.Select)
return new DbExistsExpression(select);
return exists;
}
protected virtual bool CompareExists(DbExistsExpression a, DbExistsExpression b)
{
return(Compare(a.Select, b.Select));
}
protected virtual Expression VisitExists(DbExistsExpression exists)
{
DbSelectExpression select = (DbSelectExpression)Visit(exists.Select);
return UpdateExists(exists, select);
}
private Expression BindAnyAll(Expression source, MethodInfo method, LambdaExpression predicate, bool isRoot)
{
bool isAll = method.Name == "All";
ConstantExpression constSource = source as ConstantExpression;
if (constSource != null && !IsQuery(constSource))
{
System.Diagnostics.Debug.Assert(!isRoot);
Expression where = null;
foreach (object value in (IEnumerable)constSource.Value)
{
Expression expr = Expression.Invoke(predicate, Expression.Constant(value, predicate.Parameters[0].Type));
if (where == null)
{
where = expr;
}
else if (isAll)
{
where = where.And(expr);
}
else
{
where = where.Or(expr);
}
}
return(this.Visit(where));
}
else
{
if (isAll)
{
predicate = Expression.Lambda(Expression.Not(predicate.Body), predicate.Parameters.ToArray());
}
if (predicate != null)
{
source = Expression.Call(typeof(Queryable), "Where", method.GetGenericArguments(), source, predicate);
}
DbProjectionExpression projection = this.VisitSequence(source);
Expression result = new DbExistsExpression(projection.Select);
if (isAll)
{
result = Expression.Not(result);
}
if (isRoot)
{
if (this.mapping.Language.AllowSubqueryInSelectWithoutFrom)
{
return(GetSingletonSequence(result, "SingleOrDefault"));
}
else
{
// use count aggregate instead of exists
var newSelect = projection.Select.SetColumns(
new[] { new DbColumnDeclaration("value", new DbAggregateExpression(typeof(int), DbAggregateType.Count, null, false)) }
);
var colx = new DbColumnExpression(typeof(int), null, newSelect.Alias, "value");
var exp = isAll
? colx.Equal(Expression.Constant(0))
: colx.GreaterThan(Expression.Constant(0));
return(new DbProjectionExpression(
newSelect, exp, Aggregator.Aggregate(typeof(bool), typeof(IEnumerable <bool>))
));
}
}
return(result);
}
}
private Expression BindAnyAll(Expression source, MethodInfo method, LambdaExpression predicate, bool isRoot)
{
bool isAll = method.Name == "All";
ConstantExpression constSource = source as ConstantExpression;
if (constSource != null && !IsQuery(constSource))
{
System.Diagnostics.Debug.Assert(!isRoot);
Expression where = null;
foreach (object value in (IEnumerable)constSource.Value)
{
Expression expr = Expression.Invoke(predicate, Expression.Constant(value, predicate.Parameters[0].Type));
if (where == null)
{
where = expr;
}
else if (isAll)
{
where = where.And(expr);
}
else
{
where = where.Or(expr);
}
}
return this.Visit(where);
}
else
{
if (isAll)
{
predicate = Expression.Lambda(Expression.Not(predicate.Body), predicate.Parameters.ToArray());
}
if (predicate != null)
{
source = Expression.Call(typeof(Queryable), "Where", method.GetGenericArguments(), source, predicate);
}
DbProjectionExpression projection = this.VisitSequence(source);
Expression result = new DbExistsExpression(projection.Select);
if (isAll)
{
result = Expression.Not(result);
}
if (isRoot)
{
if (this.mapping.Language.AllowSubqueryInSelectWithoutFrom)
{
return GetSingletonSequence(result, "SingleOrDefault");
}
else
{
// use count aggregate instead of exists
var newSelect = projection.Select.SetColumns(
new[] { new DbColumnDeclaration("value", new DbAggregateExpression(typeof(int), DbAggregateType.Count, null, false)) }
);
var colx = new DbColumnExpression(typeof(int), null, newSelect.Alias, "value");
var exp = isAll
? colx.Equal(Expression.Constant(0))
: colx.GreaterThan(Expression.Constant(0));
return new DbProjectionExpression(
newSelect, exp, Aggregator.Aggregate(typeof(bool), typeof(IEnumerable<bool>))
);
}
}
return result;
}
}
protected override Expression VisitExists(DbExistsExpression exists)
{
this.Write("EXISTS(");
this.WriteLine(Indentation.Inner);
this.Visit(exists.Select);
this.WriteLine(Indentation.Same);
this.Write(")");
this.Indent(Indentation.Outer);
return exists;
}
protected virtual bool CompareExists(DbExistsExpression a, DbExistsExpression b)
{
return Compare(a.Select, b.Select);
}
protected virtual Expression VisitExists(DbExistsExpression exists)
{
DbSelectExpression select = (DbSelectExpression)Visit(exists.Select);
return(UpdateExists(exists, select));
}
